1. Field of the Invention
The present invention relates to a zero point position-determining mechanism for pressurized fluid-driven apparatuses, which is applied to a pressurized fluid-driven apparatus such as a lubricator and which makes it possible to determine the position of a state in which the amount of dripped oil is zero.
2. Description of the Related Art
FIG. 9 shows a zero point mechanism of a lubricator concerning a conventional technique. The zero point mechanism 1 includes, at its outer circumference, a knob 3 formed with recesses 2 for indicating the lubrication amount or the oil supply amount. The knob 3 is rotatably supported with respect to a body 4. A ring-shaped scale plate 5, which surrounds the knob 3, is installed on the upper surface of the body 4.
The process for assembling the zero point mechanism 1 concerning the conventional technique will be briefly explained. At first, the knob 3 is rotatably assembled to the body 4. After that, the scale of "0" marked on the scale plate 5 is adjusted to the recess 2 of the knob 3, and thus the scale plate 5 is fixed to an annular projection 6 provided on the upper surface of the body 4.
However, in the case of the zero point mechanism 1 concerning the conventional technique described above, the position of the recess 2 for indicating the lubrication amount is diverse, and it is not unified depending on the situation or degree of the knob 3 assembled with respect to the body 4. In other words, the assembling operation is not performed in a state in which the recess 2 of the knob 3 is positioned at a predetermined position. In the conventional technique, a method is adopted, in which the zero point position (scale of "0") of the scale plate 5 is adjusted to the position of the recess 2 after the knob 3 is assembled, and then the scale plate 5 is fixed to the upper surface of the body 4.
Therefore, the zero point position of the scale plate 5 fixed on the upper surface of the body 4 is not mutually unified among identical products. For this reason, when an operator grips the knob 3 to adjust the lubrication amount (dripping amount of oil), it is impossible to easily perform the operation, resulting in an inconvenience that the operability is inferior.